Want to play Valve's zombie shooter Left 4 Dead 2 on a PC with Kinect? You can. All you need is the Kinect sensor, a PC, a copy of the game, and MxR Labs' FAAST, or Flexible Action and Articulated Skeleton Toolkit.
In case you're wondering what's going on in the still shot at left (from the YouTube demonstration video), a guy is mapping gestures to the game commands, and then executing actions like "move right arm" to aim, "place right foot forward" to walk, and "lift right foot" to jump. It's a lot to remember, and I count as many as 16 discrete gestures here, but if you're cool with turning flashlights on with your feet and kicking enemies with your arms, grab a copy of FAAST and go to town.